How to Clean and Repair DE Pool Filter Grids
Why Can't I Just Backwash the Filter?
Diatamaceous earth (or D.E.) filters require a full maintenance about once per year, or if your filter pressure becomes increasingly higher even after backwashing, this may require the filter to be pulled apart and cleaned. The DE powder can become caked onto the grids over a period of time, after which backwashing alone will not remove the residue. It has to be dismantled and cleaned. This is a relatively easy process and can save you quite a bit of money by avoiding a pool company's charge for this. My fee is usually $75 per a D.E. filter dismantle and clean, but I have seen companies charge upwards of $150 for this!
Taking the Filter Apart
- Before you actually begin to dis-assemble the filter, make sure you backwash it thoroughly to rinse away any loose D.E.
- Next, turn off the breaker or timer switch.
- Most brands and models will most always have a center ring known as a large band clamp around the center. This will need to be removed. It is best to use a box-end wrench to remove the clamp. The clamps vary in bolt size—some are a 9/16 others are larger.
- The entire grid assembly should be removed as shown.
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Cleaning the Grids
- As you can see in the picture, this is the filter grid assembly. The caked on DE will need to be rinsed off with a hose—if using a standard hose nozzle, make sure it is on the jet setting. You need a strong stream to remove the residue. Rinse all over the grids including in between the inside grids. Inspect the grids and top manifold thoroughly.
- Grids may be worn or torn and require replacement. If they are torn, you will not effectively be able to filter the pool water. If the top manifold is cracked, it will also require replacement.
- If all is well with the grids and manifold, finalize the rinse with a 50% water/muriatic acid solution. Pour liberally over the entire grid assembly. Let soak for 5 minutes and rinse. (Watch for fumes, as they can be overwhelming!)
- Rinse again and replace the grid assembly exactly as you removed it. Inspect and lubricate all O-rings.
Be Sure It Works
After the filter is re-assembled and the main band clamp is tightened, turn the pump on and check for any leaking around the main band clamp. If there is leakage, you will need to remove the clamp and re-inspect the O-ring making sure the top half of the filter is seated properly onto the bottom half with no twists in the O-ring.
If all is well, add your DE through the skimmer and be sure that no DE powder is returning into the pool. If any DE returns to the pool, this is a serious indication that a grid is torn or the manifold is cracked.
Questions & Answers
Cleaned the DE filter as recommended. However, a week later and the pool still remains cloudy. The filter is 10 years old. Is it time for a new one?
The filter grids might not be holding DE powder. This could be from torn grids, or a broken manifold. To test this, backwash the filter. Then add some DE powder through the skimmer. If you can see the DE powder blowing back into the pool then the filter needs repaired or replaced. If the filter has no issues and is holding DE this means the cloudy pool water has a chemistry issue, or the pump is not running long enough.